The tRNA world.
D000818:Animals; D019295:Computational Biology; D019143:Evolution, Molecular; D006801:Humans; D008928:Mitochondria / Q000502:physiology; D012343:RNA, Transfer / Q000502:physiology*; D012260:Ribonucleases / Q000502:physiology
D012343:RNA, Transfer; D012260:Ribonucleases